System and method for exchanging encryption keys between a mobile device and a peripheral output device

ABSTRACT

Systems and methods for providing additional security for data being transmitted across a wireless connection that has been established using a known wireless protocol (e.g. Bluetooth) are described. An encryption key is exchanged between a computing device (e.g. a mobile device) and a wireless peripheral output device (e.g. a printer, a headset). In some embodiments, the encryption key is generated at the peripheral output device. Data associated with the encryption key is output at the peripheral output device, which can be input by the user at the computing device. The encryption key is then recovered at the computing device from the input, thereby completing the key exchange. The encryption key can then be used to encrypt and decrypt data transmitted over the established wireless connection, providing additional security.

RELEVANT FIELD

Embodiments of the invention relate generally to wireless peripheraldevices for use with computing devices. More specifically, at least someof the embodiments described herein relate to a system and method forsecurely exchanging an encryption key between a wireless peripheraldevice and a mobile device.

BACKGROUND

Bluetooth is a known, short-range wireless technology used to connect awide range of devices. It is a globally available standard that is,currently, widely supported. Bluetooth technology provides a number ofsecurity features, including personal identification number (PIN)authentication and the encryption of data transmitted between paireddevices. After Bluetooth-capable devices identify themselves to eachother, a PIN code is used the first time they connect. The PIN is a fouror more digit alphanumeric code that is typically fixed for peripheraloutput devices, such as printers, for example, for the purpose ofpairing with another device to which a Bluetooth wireless connection isdesired.

Some experts believe that Bluetooth connections, for which securitydepends on the secure pairing of devices based on the PIN, areinherently insecure, particularly when the length of the PIN (e.g.typically four digits) is small. Some organizations that would requirepotentially sensitive data to be communicated between a mobile deviceand a wireless peripheral output device may not consider the level ofsecurity afforded by the current Bluetooth standard alone to besufficient.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of embodiments of the systems and methodsdescribed herein, and to show more clearly how they may be carried intoeffect, reference will be made, by way of example, to the accompanyingdrawings in which:

FIG. 1 is a block diagram of a mobile device in one exampleimplementation;

FIG. 2 is a block diagram of a communication subsystem component of themobile device of FIG. 1;

FIG. 3 is a block diagram of a node of a wireless network;

FIG. 4A is a block diagram illustrating components of a systemcomprising a mobile device and a wireless peripheral device for usetherewith;

FIG. 4B is a flowchart illustrating steps of a method of exchanging anencryption key between the mobile device and the wireless peripheraldevice of the system shown in FIG. 4A;

FIG. 5A is a block diagram illustrating components of the system shownin FIG. 4A where the wireless peripheral device is a keyboard;

FIG. 5B is a flowchart illustrating steps of a method of exchanging anencryption key between the mobile device and the keyboard of the systemshown in FIG. 5A;

FIG. 6A is a block diagram illustrating components of the system shownin FIG. 4A where the wireless peripheral device is a printer;

FIG. 6B is a flowchart illustrating steps of a method of exchanging anencryption key between the mobile device and the printer of the systemshown in FIG. 6A; and

FIG. 7 is a flowchart illustrating steps of a method of exchanging anencryption key between the mobile device and the wireless peripheraldevice of the system shown in FIG. 4A, in a variant embodiment.

DETAILED DESCRIPTION

Embodiments of the systems and methods described herein relate generallyto wireless peripheral devices for use with computing devices, and inrespect of at least one embodiment, more specifically to a system andmethod for securely exchanging an encryption key between a wirelessperipheral output device and a mobile device. The encryption key, oncemade available at both the wireless peripheral output device and themobile device, may be subsequently used to encrypt and/or decrypt datatransmitted between the two devices.

In one broad aspect, there is provided a method of exchanging anencryption key between a computing device and a wireless peripheraloutput device, the method comprising the steps of: generating anencryption key at the peripheral device; outputting data associated withthe encryption key to a user at the peripheral device; receiving thedata associated with the encryption key input by the user at thecomputing device; recovering the encryption key at the computing devicefrom the data associated with the encryption key input by the user; andtransmitting data encrypted with the encryption key over a wirelessconnection between the computing device and the peripheral device, thewireless connection established in accordance with a wireless protocol.

In another broad aspect, there is provided a method of exchanging anencryption key between a computing device and a wireless printer, themethod comprising the steps of: generating an encryption key at theprinter; outputting data associated with the encryption key to a user atthe printer; receiving the data associated with the encryption key inputby the user at the computing device; recovering the encryption key atthe computing device from the data associated with the encryption keyinput by the user; and transmitting data encrypted with the encryptionkey over a wireless connection between the computing device and theprinter, the wireless connection established in accordance with awireless protocol.

In exemplary embodiments, the computing device is a mobile device.

Features of these and other aspects, and of a number of embodiments ofsystems and methods are described below.

The description of some embodiments of the systems and methods describedherein make reference to a mobile device, also known in the art as amobile station. A mobile device is a two-way communication device withadvanced data communication capabilities having the capability tocommunicate with other computer systems. A mobile device may alsoinclude the capability for voice communications. Depending on thefunctionality provided by a mobile device, it may be referred to as adata messaging device, a two-way pager, a cellular telephone with datamessaging capabilities, a wireless Internet appliance, or a datacommunication device (with or without telephony capabilities). A mobiledevice communicates with other devices through a network of transceiverstations.

To aid the reader in understanding the structure of a mobile device andhow it communicates with other devices, reference is made to FIGS. 1through 3.

Referring first to FIG. 1, a block diagram of a mobile device in oneexample implementation is shown generally as 100. Mobile device 100comprises a number of components, the controlling component beingmicroprocessor 102. Microprocessor 102 controls the overall operation ofmobile device 100. Communication functions, including data and voicecommunications, are performed through communication subsystem 104.Communication subsystem 104 receives messages from and sends messages toa wireless network 200. In this example implementation of mobile device100, communication subsystem 104 is configured in accordance with theGlobal System for Mobile Communication (GSM) and General Packet RadioServices (GPRS) standards. The GSM/GPRS wireless network is usedworldwide and it is expected that these standards will be supersededeventually by Enhanced Data GSM Environment (EDGE) and Universal MobileTelecommunications Service (UMTS). New standards are still beingdefined, but it is believed that they will have similarities to thenetwork behaviour described herein, and it will also be understood bypersons skilled in the art that the invention is intended to use anyother suitable standards that are developed in the future. The wirelesslink connecting communication subsystem 104 with network 200 representsone or more different Radio Frequency (RF) channels, operating accordingto defined protocols specified for GSM/GPRS communications. With newernetwork protocols, these channels are capable of supporting both circuitswitched voice communications and packet switched data communications.

Although the wireless network associated with mobile device 100 is aGSM/GPRS wireless network in one example implementation of mobile device100, other wireless networks may also be associated with mobile device100 in variant implementations. Different types of wireless networksthat may be employed include, for example, data-centric wirelessnetworks, voice-centric wireless networks, and dual-mode networks thatcan support both voice and data communications over the same physicalbase stations. Combined dual-mode networks include, but are not limitedto, Code Division Multiple Access (CDMA) or CDMA2000 networks, GSM/GPRSnetworks (as mentioned above), and future third-generation (3G) networkslike EDGE and UMTS. Some older examples of data-centric networks includethe Mobitex™ Radio Network and the DataTAC™ Radio Network. Examples ofolder voice-centric data networks include Personal Communication Systems(PCS) networks like GSM and Time Division Multiple Access (TDMA)systems.

Other network communication technologies that may be employed include,for example, Integrated Digital Enhanced Network (iDEN™), Evolution-DataOptimized (EV-DO), and High Speed Downlink Packet Access (HSDPA).

Microprocessor 102 also interacts with additional subsystems such as aRandom Access Memory (RAM) 106, flash memory 108, display 110, auxiliaryinput/output (I/O) subsystem 112, serial port 114, keyboard 116, speaker118, microphone 120, short-range communications 122 and other devices124.

Some of the subsystems of mobile device 100 performcommunication-related functions, whereas other subsystems may provide“resident” or on-device functions. By way of example, display 110 andkeyboard 116 may be used for both communication-related functions, suchas entering a text message for transmission over network 200, anddevice-resident functions such as a calculator or task list. Operatingsystem software used by microprocessor 102 is typically stored in apersistent store such as flash memory 108, which may alternatively be aread-only memory (ROM) or similar storage element (not shown). Thoseskilled in the art will appreciate that the operating system, specificdevice applications, or parts thereof, may be temporarily loaded into avolatile store such as RAM 106.

Mobile device 100 may send and receive communication signals overnetwork 200 after required network registration or activation procedureshave been completed. Network access is associated with a subscriber oruser of a mobile device 100. To identify a subscriber, mobile device 100requires a Subscriber Identity Module or “SIM” card 126 to be insertedin a SIM interface 128 in order to communicate with a network. SIM 126is one type of a conventional “smart card” used to identify a subscriberof mobile device 100 and to personalize the mobile device 100, amongother things. Without SIM 126, mobile device 100 is not fullyoperational for communication with network 200. By inserting SIM 126into SIM interface 128, a subscriber can access all subscribed services.Services could include: web browsing and messaging such as e-mail, voicemail, Short Message Service (SMS), and Multimedia Messaging Services(MMS). More advanced services may include: point of sale, field serviceand sales force automation. SIM 126 includes a processor and memory forstoring information. Once SIM 126 is inserted in SIM interface 128, itis coupled to microprocessor 102. In order to identify the subscriber,SIM 126 contains some user parameters such as an International MobileSubscriber Identity (IMSI). An advantage of using SIM 126 is that asubscriber is not necessarily bound to any single physical mobiledevice. SIM 126 may store additional subscriber information for a mobiledevice as well, including datebook (or calendar) information and recentcall information.

Mobile device 100 is a battery-powered device and includes a batteryinterface 132 for receiving one or more rechargeable batteries 130.Battery interface 132 is coupled to a regulator (not shown), whichassists battery 130 in providing power V+ to mobile device 100. Althoughcurrent technology makes use of a battery, future technologies such asmicro fuel cells may provide the power to mobile device 100.

Microprocessor 102, in addition to its operating system functions,enables execution of software applications on mobile device 100. A setof applications that control basic device operations, including data andvoice communication applications, will normally be installed on mobiledevice 100 during its manufacture. Another application that may beloaded onto mobile device 100 would be a personal information manager(PIM). A PIM has functionality to organize and manage data items ofinterest to a subscriber, such as, but not limited to, e-mail, calendarevents, voice mails, appointments, and task items. A PIM application hasthe ability to send and receive data items via wireless network 200. PIMdata items may be seamlessly integrated, synchronized, and updated viawireless network 200 with the mobile device subscriber's correspondingdata items stored and/or associated with a host computer system. Thisfunctionality creates a mirrored host computer on mobile device 100 withrespect to such items. This can be particularly advantageous where thehost computer system is the mobile device subscriber's office computersystem.

Additional applications may also be loaded onto mobile device 100through network 200, auxiliary I/O subsystem 112, serial port 114,short-range communications subsystem 122, or any other suitablesubsystem 124. This flexibility in application installation increasesthe functionality of mobile device 100 and may provide enhancedon-device functions, communication-related functions, or both. Forexample, secure communication applications may enable electroniccommerce functions and other such financial transactions to be performedusing mobile device 100.

Serial port 114 enables a subscriber to set preferences through anexternal device or software application and extends the capabilities ofmobile device 100 by providing for information or software downloads tomobile device 100 other than through a wireless communication network.The alternate download path may, for example, be used to load anencryption key onto mobile device 100 through a direct and thus reliableand trusted connection to provide secure device communication.

Short-range communications subsystem 122 provides for communicationbetween mobile device 100 and different systems or devices, without theuse of network 200. For example, short-range communication subsystem 122may include an infrared device and associated circuits and componentsfor short-range communication. The short-range communication subsystem122 can be used to communicate with a Wireless Personal Area network(WPAN). In some cases, the short-range communications subsystem 122 cancomprise a Bluetooth radio, a ZigBee device, a Wireless USB (WUSB)device, and/or an Ultra-Wideband (UWB) radio, for example. Examples ofshort range communication standards include standards developed by theInfrared Data Association (IrDA), Bluetooth, ZigBee, WUSB, UWB, and the802.11 and 802.15 families of standards developed by IEEE.

In use, a received signal such as a text message, an e-mail message, orweb page download will be processed by communication subsystem 104 andinput to microprocessor 102. Microprocessor 102 will then process thereceived signal for output to display 110 or alternatively to auxiliaryI/O subsystem 112. A subscriber may also compose data items, such ase-mail messages, for example, using keyboard 116 in conjunction withdisplay 110 and possibly auxiliary I/O subsystem 112. Auxiliary I/Osubsystem 112 may include devices such as: a touch screen, mouse, trackball, infrared fingerprint detector, or a roller wheel with dynamicbutton pressing capability. Keyboard 116 is an alphanumeric keyboardand/or telephone-type keypad. A composed item may be transmitted overnetwork 200 through communication subsystem 104.

For voice communications, the overall operation of mobile device 100 issubstantially similar, except that the received signals would be outputto speaker 118, and signals for transmission would be generated bymicrophone 120. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on mobiledevice 100. Although voice or audio signal output is accomplishedprimarily through speaker 118, display 110 may also be used to provideadditional information such as the identity of a calling party, durationof a voice call, or other voice call related information.

Referring now to FIG. 2, a block diagram of the communication subsystemcomponent 104 of FIG. 1 is shown. Communication subsystem 104 comprisesa receiver 150, a transmitter 152, one or more embedded or internalantenna elements 154, 156, Local Oscillators (LOs) 158, and a processingmodule such as a Digital Signal Processor (DSP) 160.

The particular design of communication subsystem 104 is dependent uponthe network 200 in which mobile device 100 is intended to operate, thusit should be understood that the design illustrated in FIG. 2 servesonly as one example. Signals received by antenna 154 through network 200are input to receiver 150, which may perform such common receiverfunctions as signal amplification, frequency down conversion, filtering,channel selection, and analog-to-digital (A/D) conversion. A/Dconversion of a received signal allows more complex communicationfunctions such as demodulation and decoding to be performed in DSP 160.In a similar manner, signals to be transmitted are processed, includingmodulation and encoding, by DSP 160. These DSP-processed signals areinput to transmitter 152 for digital-to-analog (D/A) conversion,frequency up conversion, filtering, amplification and transmission overnetwork 200 via antenna 156. DSP 160 not only processes communicationsignals, but also provides for receiver and transmitter control. Forexample, the gains applied to communication signals in receiver 150 andtransmitter 152 may be adaptively controlled through automatic gaincontrol algorithms implemented in DSP 160.

The wireless link between mobile device 100 and a network 200 maycontain one or more different channels, typically different RF channels,and associated protocols used between mobile device 100 and network 200.A RF channel is a limited resource that must be conserved, typically dueto limits in overall bandwidth and limited battery power of mobiledevice 100.

When mobile device 100 is fully operational, transmitter 152 istypically keyed or turned on only when it is sending to network 200 andis otherwise turned off to conserve resources. Similarly, receiver 150is periodically turned off to conserve power until it is needed toreceive signals or information (if at all) during designated timeperiods.

Referring now to FIG. 3, a block diagram of a node of a wireless networkis shown as 202. In practice, network 200 comprises one or more nodes202. Mobile device 100 communicates with a node 202 within wirelessnetwork 200. In the example implementation of FIG. 3, node 202 isconfigured in accordance with General Packet Radio Service (GPRS) andGlobal Systems for Mobile (GSM) technologies. Node 202 includes a basestation controller (BSC) 204 with an associated tower station 206, aPacket Control Unit (PCU) 208 added for GPRS support in GSM, a MobileSwitching Center (MSC) 210, a Home Location Register (HLR) 212, aVisitor Location Registry (VLR) 214, a Serving GPRS Support Node (SGSN)216, a Gateway GPRS Support Node (GGSN) 218, and a Dynamic HostConfiguration Protocol (DHCP) 220. This list of components is not meantto be an exhaustive list of the components of every node 202 within aGSM/GPRS network, but rather a list of components that are commonly usedin communications through network 200.

In a GSM network, MSC 210 is coupled to BSC 204 and to a landlinenetwork, such as a Public Switched Telephone Network (PSTN) 222 tosatisfy circuit switched requirements. The connection through PCU 208,SGSN 216 and GGSN 218 to the public or private network (Internet) 224(also referred to herein generally as a shared network infrastructure)represents the data path for GPRS capable mobile devices. In a GSMnetwork extended with GPRS capabilities, BSC 204 also contains a PacketControl Unit (PCU) 208 that connects to SGSN 216 to controlsegmentation, radio channel allocation and to satisfy packet switchedrequirements. To track mobile device location and availability for bothcircuit switched and packet switched management, HLR 212 is sharedbetween MSC 210 and SGSN 216. Access to VLR 214 is controlled by MSC210.

Station 206 is a fixed transceiver station. Station 206 and BSC 204together form the fixed transceiver equipment. The fixed transceiverequipment provides wireless network coverage for a particular coveragearea commonly referred to as a “cell”. The fixed transceiver equipmenttransmits communication signals to and receives communication signalsfrom mobile devices within its cell via station 206. The fixedtransceiver equipment normally performs such functions as modulation andpossibly encoding and/or encryption of signals to be transmitted to themobile device in accordance with particular, usually predetermined,communication protocols and parameters, under control of its controller.The fixed transceiver equipment similarly demodulates and possiblydecodes and decrypts, if necessary, any communication signals receivedfrom mobile device 100 within its cell. Communication protocols andparameters may vary between different nodes. For example, one node mayemploy a different modulation scheme and operate at differentfrequencies than other nodes.

For all mobile devices 100 registered with a specific network, permanentconfiguration data such as a user profile is stored in HLR 212. HLR 212also contains location information for each registered mobile device andcan be queried to determine the current location of a mobile device. MSC210 is responsible for a group of location areas and stores the data ofthe mobile devices currently in its area of responsibility in VLR 214.Further VLR 214 also contains information on mobile devices that arevisiting other networks. The information in VLR 214 includes part of thepermanent mobile device data transmitted from HLR 212 to VLR 214 forfaster access. By moving additional information from a remote HLR 212node to VLR 214, the amount of traffic between these nodes can bereduced so that voice and data services can be provided with fasterresponse times and at the same time require less use of computingresources.

SGSN 216 and GGSN 218 are elements added for GPRS support, namely packetswitched data support, within GSM. SGSN 216 and MSC 210 have similarresponsibilities within wireless network 200 by keeping track of thelocation of each mobile device 100. SGSN 216 also performs securityfunctions and access control for data traffic on network 200. GGSN 218provides internetworking connections with external packet switchednetworks and connects to one or more SGSN's 216 via an Internet Protocol(IP) backbone network operated within the network 200. During normaloperations, a given mobile device 100 must perform a “GPRS Attach” toacquire an IP address and to access data services. This requirement isnot present in circuit switched voice channels as Integrated ServicesDigital Network (ISDN) addresses are used for routing incoming andoutgoing calls. Currently, all GPRS capable networks use private,dynamically assigned IP addresses, thus requiring a DHCP server 220connected to the GGSN 218. There are many mechanisms for dynamic IPassignment, including using a combination of a Remote AuthenticationDial-In User Service (RADIUS) server and DHCP server. Once the GPRSAttach is complete, a logical connection is established from a mobiledevice 100, through PCU 208, and SGSN 216 to an Access Point Node (APN)within GGSN 218. The APN represents a logical end of an IP tunnel thatcan either access direct Internet compatible services or private networkconnections. The APN also represents a security mechanism for network200, insofar as each mobile device 100 must be assigned to one or moreAPNs and mobile devices 100 cannot exchange data without firstperforming a GPRS Attach to an APN that it has been authorized to use.The APN may be considered to be similar to an Internet domain name suchas “myconnection.wireless.com”.

Once the GPRS Attach is complete, a tunnel is created and all traffic isexchanged within standard IP packets using any protocol that can besupported in IP packets. This includes tunneling methods such as IP overIP as in the case with some IPSecurity (IPsec) connections used withVirtual Private Networks (VPN). These tunnels are also referred to asPacket Data Protocol (PDP) Contexts and there are a limited number ofthese available in the network 200. To maximize use of the PDP Contexts,network 200 will run an idle timer for each PDP Context to determine ifthere is a lack of activity. When a mobile device 100 is not using itsPDP Context, the PDP Context can be deallocated and the IP addressreturned to the IP address pool managed by DHCP server 220.

At least some of the embodiments described herein are directed to asystem and method for securely exchanging an encryption key between awireless peripheral device and a mobile device.

Some experts believe that connections between Bluetooth devices, ofwhich security depends on the secure pairing of the devices based on aPIN, are inherently insecure, particularly where the length of the PIN(e.g. typically four digits) is small. Furthermore, security may also becompromised if the pairing process is not performed in private.

Accordingly, in at least one embodiment, means for providing additionalsecurity for data being transmitted across a wireless connection thathas been established using a known wireless protocol (e.g. Bluetooth) isdescribed herein. More specifically, embodiments of a system and methodfor exchanging an encryption key between a mobile device and a wirelessperipheral device are described herein, where the encryption key can besubsequently used to encrypt and/or decrypt data transmitted between thetwo devices across the established wireless connection.

In these embodiments, the encryption key that is exchanged between themobile device and the wireless peripheral device is unrelated to (i.e.not derivable from) any PIN that may be used to pair two (e.g.Bluetooth-enabled) devices, for example. This provides additionalsecurity, as a brute force recovery of the PIN would not aid anymalicious attempt to uncover the exchanged encryption key, which couldthen be used to decrypt potentially sensitive data that is transmittedbetween the two devices.

Furthermore, the security associated with the subsequent use of anexchanged encryption key is provided in addition to any security that isinherent in the underlying established wireless connection. For example,depending on the security mode for Bluetooth access that has beenenabled between two devices, data being transmitted across a Bluetoothconnection between the two devices can be encrypted as the Bluetoothstandard provides for data encryption capability. However, theadditional security afforded by the use of the encryption key exchangedin accordance with an embodiment described herein would be provided todata transmitted over the Bluetooth connection, whether the built-inBluetooth data encryption capability has been enabled or not.

By allowing additional security to be introduced in a manner that isindependent of the protocol used to establish the underlying (e.g.Bluetooth) wireless connection, greater flexibility may be provided. Forexample, it may be easier to modify existing devices that are alreadycapable of establishing wireless connections in accordance with a knownprotocol, in order to provide the additional security. As a furtherexample, once two devices are paired or otherwise connected, newencryption keys that may be used to provide the additional security cangenerally be exchanged at any desired time, and at any desiredfrequency, between the devices.

In exemplary embodiments, the encryption key used to provide additionalsecurity is a key that is used to encrypt and decrypt data in accordancewith a symmetric encryption technique, such as the Advanced EncryptionStandard (AES), Data Encryption Standard (DES), or Triple DES (3DES),for example. In order for both the mobile device and the wirelessperipheral device to be capable of encrypting and decrypting the datathat each device is to transmit to the other over the established (e.g.Bluetooth) wireless connection, there is a need for a secure means toexchange the encryption key to be used between the two devices.

It will be understood by persons skilled in the art that the act ofexchanging an encryption key need not involve the transmission of theactual encryption key itself from one device to the other. It will alsobe understood that it is not necessary that an actual encryption key beinitially generated at only one device and then subsequently transferredto the other device in order to constitute an “exchange”. It issufficient that the encryption key to be used is derived at or otherwisebecomes known to each device, through the processing of some data thatis shared between the two devices. In that case, a key “exchange” isdeemed to have occurred.

Referring to FIGS. 4A and 4B, a block diagram illustrating components ofa system comprising a mobile device and a wireless peripheral device foruse therewith, and a flowchart illustrating steps of a method ofexchanging an encryption key between the mobile device and the wirelessperipheral device, in at least one embodiment, are shown generally as300 and 330 respectively.

In FIG. 4A, a system 300 comprising a mobile device 100 coupled to aperipheral device 310 via a wireless connection 320 is shown. Inexemplary embodiments, mobile device 100 comprises a short-rangecommunications subsystem (e.g. 122 of FIG. 1) to facilitate wirelesscommunication with peripheral device 310 over wireless connection 320.Wireless connection 320 may be a Bluetooth connection, for example.

In one embodiment, peripheral device 310 is a device that provideskeyboard or keypad input capabilities, as described in greater detailbelow with reference to FIGS. 5A and 5B. In another embodiment,peripheral device 310 is a device that provides printing capabilities,as described in greater detail below with reference to FIGS. 6A and 6B.In variant embodiments, peripheral device 310 will be some other devicewith either input and/or output capabilities.

Referring now to FIG. 4B, method 330 commences with the establishment ofthe wireless connection 320 between the mobile device 100 and theperipheral device 310 in accordance with a known wireless protocol (e.g.Bluetooth), at step 332.

If wireless connection 320 is a Bluetooth connection, step 332 maycomprise configuring both devices so that they are made visible forpairing, placing both devices into a pairing mode, and completing apairing process in known manner. In the pairing process, a PIN codegenerated by one device or otherwise fixedly associated with the onedevice is entered into the other device via a user interface, and thetwo devices subsequently validate each other.

In exemplary embodiments, a software application that executes on mobiledevice 100 (e.g. by microprocessor 102 of FIG. 1) is programmed toperform at least a first subset of the steps of method 330, and asoftware application that executes on peripheral device 310 (e.g. asfirmware of peripheral device 310) is programmed to perform at least asecond subset of the steps of method 330. In variant embodiments, theinstructions to perform some or all of the steps of method 330 may beembedded in hardware.

At step 334, both the mobile device 100 and the peripheral device 310are placed into an “additional security” operational mode, whichindicates that data transmissions are to be encrypted with an encryptionkey that is to be exchanged between the two devices as described herein.

Mobile device 100 may be placed into the additional security operationalmode, for example, in response to a user request (e.g. the user manuallyselects a corresponding configuration option at the mobile device 100),automatically after pairing has been completed at step 332, orautomatically in accordance with a pre-defined schedule. The manner inwhich mobile device 100 can be placed into the additional securityoperational mode may be reflected in configuration settings on mobiledevice 100. In variant embodiments, the values of the configurationsettings may be set in accordance with a security policy (“IT Policy”)governing the use of mobile device 100.

Similarly, peripheral device 310 may be placed into the additionalsecurity operational mode, for example, in response to a user request(e.g. the user manually operates a button on the peripheral device in apre-specified manner), automatically after pairing has been completed atstep 332, or automatically in accordance with a pre-defined schedule.

Placing both devices into the additional security operational mode mayrequire that action be independently taken at each device.Alternatively, a first of two devices may be placed into the additionalsecurity operational mode (either automatically or in response to userinput), which subsequently triggers the transmission of a command to thesecond of the two devices over the wireless connection 320. In thelatter case, placement of the second device into the additional securityoperational mode is performed automatically upon receipt of the commandat the second device from the first device.

At step 336, an encryption key is generated at one of the mobile device100 and the peripheral device 310, in accordance with a key-generatingalgorithm. For example, the key-generating algorithm may produce arandom 128-bit, 196-bit, or 256-bit number. The one device at which theencryption key is generated at this step needs to be capable ofproviding output to a user, while the other of the two devices must becapable of receiving input from the user. The generated encryption keyis then typically stored at the one device [step not explicitly shown].

Optionally, at step 338, the encryption key generated at step 338 isconverted into new data, preferably in a more user-friendly format,using a key-conversion algorithm. The key-conversion algorithm that isused must allow the encryption key to be recoverable from the new data(with possibly some other data). Therefore, for example, a hashingfunction would generally be inappropriate for performing the conversionat this step.

The format that may be employed for the new data may depend on the inputcapabilities of the other of the mobile device 100 and the peripheraldevice 310. For instance, an encryption key may be converted into ashorter alphanumeric string, if the other device is capable of receivingsuch strings as input.

In one embodiment, the key-conversion algorithm simply converts a binarykey into a hexadecimal number, and produces the hexadecimal number asthe string, for example.

At step 340, data is output to a user at the one device where theencryption key was generated at step 336. Where step 338 is notperformed, the data output at step 340 might comprise the actualencryption key. However, more typically, the data output at step 340will comprise the new data generated from the conversion of theencryption key as performed at step 338.

The data output to the user at step 340 might be, for example, shown ina display (e.g. a liquid crystal display (LCD)), written to a physicalmedium (e.g. paper, disk), provided in an audio format (e.g. peripheraldevice 310 may be a headset or speaker, and the headset or speaker couldfurther convert a string or number into speech to be output to theuser), or presented on a touch-based device (e.g. Braille pad).Additional instructions and other information to be considered by theuser may also be provided with the data that is output at this step.

In operation, after the data is output to a user at step 340 at one ofthe mobile device 100 and the peripheral device 310, the user will inputthe data at the other of the two devices, via a user interface providedat the other device. The data is not transmitted over the wirelessconnection 320.

The data input by the user is received at the other device, as shown atstep 342. For example, step 342 may comprise receiving an alphanumericstring that was generated by conversion at step 338, as user input.

At step 344, the encryption key (originally generated at step 336) isrecovered at the device receiving the data input at step 342, andsubsequently stored at that device [storing step not explicitly shown].This may require the application of an appropriate key recoverytechnique associated with the key-conversion algorithm employed at step338, if step 338 was performed. Depending on the key-conversionalgorithm being employed, recovering the encryption key may also requireprocessing other data (e.g. which may be pre-stored or otherwiseprovided to the device) in addition to the data received from the userat step 342.

Accordingly, after step 344 is performed, the encryption key isavailable at both mobile device 100 and peripheral device 310.Completion of steps 336 to 344 constitutes a secure exchange of theencryption key between the two devices.

With the encryption key now available at both devices, data may betransmitted between the devices as shown at step 346, where thetransmissions are encrypted using the encryption key in accordance witha data encryption algorithm (e.g. AES, DES, 3DES). Transmitted datareceived by a device can then be subsequently decrypted using the sameencryption key [step not explicitly shown].

The out-of-band exchange of data output at one device with the otherdevice will prevent hackers who surreptitiously monitor wirelesscommunications from intercepting the data over the wireless connectionand recovering the encryption key.

In view of the additional security provided by embodiments of method330, it will be understood that in respect of Bluetooth connections,even if a hacker were able to pair with one of two Bluetooth devices andmasquerade as the other device, the hacker would not have access to theencryption key necessary to decrypt the transmissions it receives.Moreover, the encryption key exchanged in accordance with embodimentsdescribed herein could not be derived from a PIN even if the hackermanages to uncover the PIN. Furthermore, unlike a PIN used to pairBluetooth devices that might be maliciously uncovered by the hacker(particularly when the length of the PIN is small), there is no datathat is exchanged over the established wireless connection 320 whenencrypted with an encryption key of sufficient length, that couldeffectively be used to derive the data output at step 340 at one deviceto be shared out-of-band with the other device. Effectively, the dataoutput at step 340 is non-derivable from the encrypted data transmittedbetween the two devices. The data output at step 340 is used to derivethe encryption key, and not for the purposes of pairing two devices.Accordingly, additional security is provided.

It will be understood by persons skilled in the art that some of thesteps of method 330 may be repeated. For example, new keys may beexchanged between the two devices (e.g. by repeating steps 336 to 344)in accordance with a pre-defined schedule, at a certain frequency, or asotherwise desired, automatically and/or in response to a user request.This flexibility may provide additional security without requiring a newwireless connection to be established or a pairing process to berepeated.

Furthermore, in variant embodiments, the same data may be output at onedevice (at step 340) to be input by a user at multiple other devices.The same encryption key may be recovered from this data at each of thedevices sharing the data, and used to encrypt and decrypt datatransmitted between any subset of these devices when connected, ifdesired.

Details of embodiments of method 330 have been provided above withreference to a mobile device and a general peripheral device. Additionaldetails of the method will now be provided in the description of FIGS.5B and 6B that follows, where the peripheral device is more specificallya wireless keyboard 310 a as shown in FIG. 5A, and where the peripheraldevice is more specifically a peripheral output device such as awireless printer 310 b as shown in FIG. 6A respectively. It will beunderstood, however, that method 330 may be implemented in respect ofother peripheral input and/or output devices in variant embodiments.

For example, in one variant embodiment, peripheral device 310 may be aheadset, and data is output to the user at step 340 at the headset (e.g.either as audio/speech or via a display on the headset) to be entered bythe user on the mobile device, received by the mobile device at step342.

It will be understood that there may be particular benefits associatedwith embodiments where the data is output (at step 340) at theperipheral device, and the data is input at the mobile device (receivedat step 342). In these embodiments, the data to be shared is firstgenerated at the peripheral output device (e.g. printer, headset), andnot at the mobile device. In the past, prior art peripheral outputdevices were not adapted to perform tasks related to generating dataassociated with encryption keys. This may be attributed to the fact thatthe peripheral output devices are generally not expected to perform suchprocessing tasks. Furthermore, peripheral devices capable of outputtingdata to a user are often considered to be passive devices compared tothe mobile device or other computing device to which they may beconnected.

Accordingly, greater flexibility may be provided where the data outputat step 340 is output at the peripheral device. For example, some of theprocessing tasks required in the exchange of encryption keys arediverted to the peripheral device, potentially conserving resources atthe computing device connected to the peripheral device, which may beparticularly beneficial when the computing device is a mobile device.Furthermore, the user may receive the output data from the peripheraldevice and enter it into the mobile device or other computing device,prior to when additional security is desired, at the convenience of theuser. This may, for instance, permit more efficient configuration of asystem in which keys are to be exchanged between multiple peripheraldevices and the mobile device or other computing device.

Referring to FIG. 5B, a flowchart illustrating steps of a method ofexchanging an encryption key between the mobile device and the keyboardof the system shown in FIG. 5A is shown generally as 330 a. Steps 332 ato 346 a generally correspond to steps 332 to 346 as described withreference to FIG. 4B, except that the peripheral device is morespecifically a wireless keyboard 310 a. Accordingly, the reader isdirected to the description provided herein with reference to FIGS. 4Aand 4B for details in respect of method 330 a.

In one example embodiment as shown in FIG. 5B, the encryption key isgenerated at mobile device 100 (step 336 a), which is converted to astring (step 338 a). Conversion of the key into a string format may beconsidered particularly appropriate for this specific peripheral device,since a keyboard is naturally designed to accept alphanumeric input. Thestring is then output to a user of mobile device 100 (step 340 a)through a display (e.g. 110 of FIG. 1) of mobile device 100.

In operation, the user types the string that is output at the mobiledevice 100 into wireless keyboard 310 a.

Once the keys are pressed on wireless keyboard 310 a, the charactersreceived from the user through the keyboard are converted into a string(step 342 a), which is then used to recover the encryption key (step 344a). The encryption key can then be used to encrypt and decrypt datatransmitted between mobile device 100 and wireless keyboard 310 a, inaccordance with a data encryption algorithm.

Accordingly, security can be added to data transmitted over an existingwireless connection 320 (e.g. Bluetooth) between mobile device 100 andwireless keyboard 310 a, and alteration of the hardware of wirelesskeyboard 310 a is unnecessary.

Referring to FIG. 6B, a flowchart illustrating steps of a method ofexchanging an encryption key between the mobile device and the printerof the system shown in FIG. 6A is shown generally as 330 b. Steps 332 bto 346 b generally correspond to steps 332 to 346 as described withreference to FIG. 4B, except that the peripheral device is morespecifically a peripheral output device such as wireless printer 310 b.Accordingly, the reader is directed to the description provided hereinwith reference to FIGS. 4A and 4B for details in respect of method 330b.

In one embodiment, the encryption key is generated at wireless printer310 b (step 336 b), which is converted to a string (step 338 b). Thestring is then output to a user (step 340 b) at wireless printer 310 b.For example, the printer could simply print out the string for the useron paper or on another medium.

In operation, the user enters the string output at the printer 310 binto mobile device 100. This may be done by entering the string through,for example, a keyboard (e.g. 116) integrated with mobile device 100, orthrough some other input device (e.g. touch screen) or user interface.

The string received at the mobile device (step 342 b) is then used torecover the encryption key (step 344 b). The encryption key can then beused to encrypt and decrypt data transmitted between mobile device 100and wireless printer 310 b, in accordance with a data encryptionalgorithm.

Accordingly, security can be added to data transmitted over an existingwireless connection 320 (e.g. Bluetooth) between mobile device 100 andwireless printer 310 b, and alteration of the hardware of wirelessprinter 310 b is unnecessary.

For example, Bluetooth-enabled printers usually have a fixed PINassociated with them. In atypical cases where it is possible to change afixed PIN, desktop software or some other mechanism may be required tochange the PIN. In contrast, in accordance with at least one embodiment,an encryption key can be generated every time a mobile device is pairedwith a wireless peripheral device. This provides for greater security,as the encryption key is not hard-coded in or otherwise fixedlyassociated with the peripheral device (or the mobile device), forexample.

It will be understood by persons skilled in the art that although method330 b has been described herein with reference to a wireless printer 310b, in variant embodiments, the peripheral output device may be a deviceother than a wireless printer. The manner in which output is provided tothe user at step 340 b may be modified depending on the outputcapabilities of the particular peripheral output device.

It will be understood by persons skilled in the art that the term“keyboard” is not to be limited to devices that solely provide keyboardor keypad input capabilities. Similarly, the term “printer” is not to belimited to devices that solely provide printing capabilities. Someperipheral devices may provide multiple input and/or outputcapabilities. By way of example, a given device may be considered to bea “keyboard” in respect of embodiments described with reference to FIGS.5A and 5B, while the same device may also be considered to be a“printer” in respect of embodiments described with reference to FIGS. 6Aand 6B.

More generally, a peripheral output is not restricted to peripheraldevices that solely provide output to a user. A peripheral device may beequipped with user input capabilities, but still considered to be anoutput device if it is capable of providing output to a user.

In embodiments of the invention where a string is to be output at one ofthe mobile device and the wireless peripheral device, and issubsequently input by the user at the other of the two devices, one of anumber of algorithms may be employed to convert keys into a stringformat or to recover keys from a string.

Some examples of algorithms that may be employed include, for example,Public-Key Cryptography Standard #5 (PKCS5) using password-based keyderivation function 2 (PBKDF2), and Simple Password-authenticatedExponential Key Exchange (SPEKE), or variants thereof. Some of thesealgorithms may not generate a string from an encryption key, but mayinstead be used to generate encryption keys from a string that isshared. The string to be shared may be derived from other data (e.g. apassword, random data).

Accordingly, in a variant embodiment, this string rather than an actualencryption key may instead be first generated at one of the two devices.In that case, the encryption key generated at the one device (e.g. atstep 336/336 a/336 b) is generated based on the string (which may havebeen derived from other data), using the appropriate string-to-keygeneration algorithm. In this manner, both devices will be able togenerate the encryption key.

To illustrate this variant embodiment by way of example, reference ismade to FIG. 7. Method 330 c is similar to method 330 of FIG. 4B, exceptthat the above-mentioned string is generated at step 335 c (possiblyderived from other data) and output at step 340 c at the one device, tobe received by the other device at step 342 c. In another variantembodiment, the string generated at step 335 c may be generated at athird device and provided to the one device.

The string generated at step 335 c would also be used to generate theencryption key at the one device using the string-to-key generationalgorithm at step 336 c. Step 336 c may be performed any time after step335 c, but before data is to be transmitted over the wireless connectionat step 346 c. Steps 332 c, 334 c, 344 c, and 346 c have been describedwith reference to steps 332, 334, 344, and 346 of method 330 of FIG. 4Brespectively.

In view of the foregoing, it will be understood that the term “recover”and its derivations used herein in the specification and in the claimswith reference to recovery of the encryption key (e.g. steps 344/344a/344 b/344 c) is to be interpreted broadly, and may be, for example,interchangeable with the more general term “generate” and its respectivederivations. In particular, the act of recovering an encryption key doesnot presuppose that the actual encryption key must first be generated atone device before it is recovered at the other device. For example, asnoted above in respect of certain embodiments, an encryption key may begenerated at each of two devices from the same, shared string.Accordingly, it is not necessary that an encryption key be first“generated” at one device in order that the encryption key may be“recovered” at the other device.

It will also be understood by persons skilled in the art that the orderof the steps of the above methods may be modified in variantembodiments. For example, encryption keys may be exchanged between twodevices in accordance with an embodiment of a method described hereinbefore the pairing of two devices is initiated or before a wirelessconnection between the two devices is otherwise established. In the casewhere an encryption key is “pre-exchanged” in this manner and stored,the encryption key may be subsequently retrieved and automatically usedto encrypt and decrypt data transmitted over a wireless connection oncethe wireless connection is established.

In variant embodiments of the invention, multiple keys may be generatedand exchanged between two devices. For example, public and/or privatekeys may be exchanged between the two devices, and the data encryptionalgorithm to be employed in encrypting and decrypting data transmittedover the wireless connection may be based on public key cryptography.

Although the embodiments described herein make reference to a mobiledevice and a peripheral device, in variant embodiments, encryption keysmay be exchanged between other computing devices and a peripheral devicein the manner described herein.

The steps of a method of exchanging an encryption key between acomputing device and a wireless peripheral device in embodimentsdescribed herein may be provided as executable software instructionsstored on computer-readable media, which may include transmission-typemedia.

The invention has been described with regard to a number of embodiments.However, it will be understood by persons skilled in the art that othervariants and modifications may be made without departing from the scopeof the invention as defined in the claims appended hereto.

The invention claimed is:
 1. A method of securely transmitting databetween a computing device and a peripheral device using a recoveredencryption key, the method comprising: pairing the computing device andthe peripheral device over a wireless connection; placing a first of twodevices into an additional security operational mode, the two devicescomprising the computing device and the peripheral device; triggeringtransmission of a command from the first of the two devices to a secondof the two devices over the wireless connection to cause the second ofthe two devices to enter the additional security operational mode, orreceiving a command transmitted from the second of the two devices overthe wireless connection at the first of the two devices before placingthe first of the two devices into the additional security operationalmode; generating an encryption key at the peripheral device; at theperipheral device, converting the encryption key into a shorteralphanumeric string from which the encryption key is recoverable andoutputting the shorter alphanumeric string, wherein the shorteralphanumeric string into which the encryption key was converted isprinted to paper by the same peripheral device that generated theencryption key, provided in audio format, or presented on a Braille pad;the computing device receiving, from a user interface provided by thecomputing device, the shorter alphanumeric string; recovering theencryption key at the computing device from the shorter alphanumericstring received from the user interface provided by the computingdevice; and transmitting data encrypted with the encryption key over thewireless connection between the computing device and the same peripheraldevice that generated the encryption key, the wireless connectionestablished in accordance with a wireless protocol.
 2. The method ofclaim 1, wherein the shorter alphanumeric string comprises a hexadecimalnumber.
 3. The method of claim 1, wherein the peripheral devicecomprises a headset.
 4. The method of claim 1, wherein the peripheraldevice comprises a printer.
 5. The method of claim 1, wherein at leastone of the generating, outputting, receiving and recovering is performedbefore the pairing.
 6. The method of claim 1, wherein the wirelessprotocol is Bluetooth.
 7. The method of claim 1, wherein the computingdevice comprises a mobile device.
 8. A peripheral device configured toperform a method of securely transmitting data to a computing deviceusing a recovered encryption key, the peripheral device comprising aprocessor and a memory, wherein the processor is configured to: pair theperipheral device with the computing device over a wireless connection;place the peripheral device into an additional security operationalmode; trigger transmission of a command to the computing device over thewireless connection to cause the computing device to enter theadditional security operational mode, or receive a command transmittedfrom the computing device over the wireless connection before placingthe peripheral device into the additional security operational mode;generate an encryption key at the peripheral device; at the peripheraldevice, convert the encryption key into a shorter alphanumeric stringfrom which the encryption key is recoverable and outputting the shorteralphanumeric string, wherein the shorter alphanumeric string into whichthe encryption key was converted is printed to paper by the sameperipheral device that generated the encryption key, provided in audioformat, or presented on a Braille pad; and transmit, to the computingdevice, data encrypted with the encryption key over the wirelessconnection, and receive, from the computing device, data encrypted withthe encryption key over the wireless connection, the wireless connectionestablished in accordance with a wireless protocol; wherein thecomputing device is configured to receive, from a user interfaceprovided by the computing device, the shorter alphanumeric string, andrecover the encryption key from the shorter alphanumeric string receivedfrom the user interface provided by the computing device.
 9. Theperipheral device of claim 8, wherein the shorter alphanumeric stringcomprises a hexadecimal number.
 10. The peripheral device of claim 8,wherein the peripheral device comprises a headset.
 11. The peripheraldevice of claim 8, wherein the peripheral device comprises a printer.12. The peripheral device of claim 8, wherein the wireless protocol isBluetooth.
 13. A computing device configured to perform a method ofsecurely transmitting data to a peripheral device using a recoveredencryption key, the computing device comprising a processor and amemory, wherein the processor is configured to: pair the computingdevice with the peripheral device over a wireless connection; place thecomputing device into an additional security operational mode; triggertransmission of a command to the peripheral device over the wirelessconnection to cause the peripheral device to enter the additionalsecurity operational mode, or receive a command transmitted from thecomputing device over the wireless connection before placing thecomputing device into the additional security mode; receive, from a userinterface provided by the computing device, a shorter alphanumericstring from which the encryption key is recoverable; recover theencryption key at the computing device from the shorter alphanumericstring received from the user interface provided by the computingdevice; and transmit, to the peripheral device, data encrypted with theencryption key over the wireless connection, and receive, from theperipheral device, data encrypted with the encryption key over thewireless connection, the wireless connection established in accordancewith a wireless protocol; wherein the peripheral device is configured togenerate the encryption key, convert the encryption key into a shorteralphanumeric string, and output the shorter alphanumeric string, whereinthe shorter alphanumeric string into which the encryption key wasconverted is printed to paper by the same peripheral device with whichthe wireless connection is established, provided in audio format, orpresented on a Braille pad.
 14. The computing device of claim 13,wherein the shorter alphanumeric string comprises a hexadecimal number.15. The computing device of claim 13, wherein the computing devicecomprises a mobile device.
 16. The computing device of claim 13, whereinthe wireless protocol is Bluetooth.